Lip Rolling Machine With Rotated Oven Guide Bar

ABSTRACT

A lip rolling machine for forming a lip on the rim of preformed containers such as cups, including a set of spaced apart tubular oven guide bars guiding a train of nested cups through an oven for preheating the rims thereof. One of the guide bars is driven to be rotated driven by a variable speed motor and a belt drive so as to maintain rotation of the train of cups while passing through the oven. One embodiment includes a fixed inner tube having an outer tube rotated on the inner but.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. provisional patentapplication No. 61/686,386 filed on Apr. 4, 2012.

BACKGROUND OF THE INVENTION

This invention concerns machines for the manufacture of thermoformedplastic containers, such as cups, and more particularly machines forforming a lip bead on the rim of molded cups, generally referred to aslip curling or rolling machines. Such apparatus has been known for manyyears in the industry, and is described in U.S. Pat. No. 3,337,919issued on Aug. 29, 1967 for a “Container Rim Beading Apparatus”. Thistype of machine includes a feed mechanism receiving a continuous trainof previously molded nested cups that is conveyed into a feed mechanismwhich advances and rotates the train of cups at a set rate through aheating oven and into the lip forming mechanism where the lips areformed. The train of nested cups is advanced on a set of three liquidcooled guide bars extending through the oven, the guide bars spacedaround the perimeter of the cups to contact the rims at three points.The heating of the cups in the oven softens the cup rims prior to thecups being advanced into a lip curling mechanism in order to properlycarry out the formation of the lip. The nesting of the cups exposes onlythe rims so that the oven heating is thereby concentrated on the cuprims.

Improvements to the conveyor, feed mechanism, guide bar spacingadjusting mechanisms, an oven mounting, and lip curling mechanism areall described and claimed in U.S. Pat. Nos. 6,135,754; 6.093,010; and6,164,949, assigned to the assignee of the present application, eachhereby incorporated herein by reference.

These components of the machines are each designed to be adjustable toaccommodate different size containers. The adjustable size capabilityrequires significant maintenance support, particularly in beinginitially set up for a run of each size and type of container. It iscritical that the feed rate be set to match the rate of processing ofthe cups in the lip curling screw mechanism in order that the cups stayfully nested while in the oven for proper heating of the rim only. Thatis, if the feed rate is too slow, the cups become separated and the cupbodies become partially exposed to be heated and softened. The feed ofthe cups also must not be too high as this will unduly compress thestack and cause twisting and snaking of the nested cup train in theoven. The proper feed rate is mostly a function of the stack height of agiven cup configuration, as the rate of feed of the train of nested cupsinto the curling screws necessarily varies with the number of cups perunit length in the train.

The oven encloses the train of nested cups which are guided in theirmovement through the oven by the set of three oven guide bars, which arearranged to contact the rims of the cups at three points around theirperimeter.

The guide bars are tubular and have coolant circulated therethrough at atemperature and flow rate which are controlled so as to create the justproper degree of heating of the cup rims.

The train of nested cups is rotated as well as axially advanced by thefeed mechanism at the entrance to the oven so as to produce uniformheating of the rims of the cups as they travel through the oven.

The guide bars themselves conventionally do not rotate, and frictionbetween the rotating cup rims and the stationary guide bars canappreciably retard the rotation of the train of nested cups to varyingdegrees as it moves through the oven. Any variation in the rate ofrotation of the cups in turn adversely affects the uniformity of theheating of the rims which in turn lowers the quality of formed lipsproduced in the lip forming mechanism.

The nested cup train may also not be advanced at a uniform rate due tofriction with the guide bars to also affect the heating and thereforethe lip forming process. The rate of advance of the cups must be closelymatched to the rate of operation of the lip curling mechanism as notedabove.

It is an object of the present invention to provide an arrangement in alip curling apparatus for maintaining uniform rotation and advance ofthe train of nested cups within the preheating oven to insure properheating.

SUMMARY OF THE INVENTION

The above recited object and other objects which will become apparentupon a reading of the following specification and claims are achieved byan arrangement for rotating at least one of the guide bars extendingwithin the preheating oven to thereby continue to drive and rotate thenested cup train after it leaves the feed mechanism and as it movesthrough the oven. This arrangement includes a rotational drive rotatingone guide bar which is supported on bearings while receiving a flow ofcoolant through the guide bar.

The guide bar includes a tube rotatably mounted on bearings carried by apair of stationary end piece assemblies, each of which being connectedto an arm of a respective spacing adjusting mechanisms.

A partially exposed toothed sheave is attached to one end of the tubedriven by a recirculating belt powered by a variable speed D.C. electricmotor to rotate the central hollow tube at a high speed so that thefrictional contact with the cup rims also rotates the train of nestedcups but at a much lower rate of rotation. This enables adjustment ofthe rate of rotation of the train of nested cups.

The guide bar may also be rotatable on a fixed inner tube held betweenthe end piece assemblies which receive coolant flow via a fixed fittingincluded in end piece assemblies at each end of the inner tube. An outertube may be is rotatably mounted on the inner fixed tube by heatresistant bearings and is rotated by a variable speed D.C. electricmotor driving a belt circulated around sheaves included in a belttensioner and engaging a toothed sheave fixed to the outer tube. Aclosely fit bushing is interposed between the inner fixed tube and theouter tube in order to hold the outer tube straight during its rotationto minimize any tendency to whip while being rotated due to a lack ofstraightness.

The space between the inner fixed tube and rotated outer tube ispreferably filled with oil to not only lubricate the bearings but alsoto act as a heat transfer agent conducting heat into the coolant flowingthrough the inner fixed tube which is hereby conducted away from thebearings supporting the outer tube since the coolant is kept at atemperature approximately 30° F. cooler than the surface of the outersleeve. This also extends the service life of these bearings.

In an alternative arrangement, a single tube is rotatably mounted on endfittings fixed to either end of the tube which extend within arespective end piece assembly, supported on bearings included in the endpiece assemblies. Rotary unions provide a respective fluid connectionsto a coolant source establishing flow through the single tube.

The rotated and non rotated guide bars may be slightly skewed from oneend to the other to augment the axial drive force created by the feedmechanism to aid in maintaining the axial advance of the train of nestedcups through the oven and into the lip curling mechanism.

This arrangement enables a closely controlled rate of rotation and axialfeed of the train of nested cups to reliably achieve a quality rolledlip on the rims of the cups.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic representation of the lips curling apparatus ofthe present invention.

FIGS. 2A and 2B are pictorial views of either components of the lip endcurling apparatus depicted diagrammatically in FIG. 1.

FIG. 3 is an end view of a transverse section taken through the guidebar set.

FIG. 3A is a view of a transverse section through the guide bar setlooking in the opposite direction.

FIG. 3B is a fragmentary top view of the guide bar drive motor andassociated components.

FIG. 4 is a top view of a rotated guide bar broken away in the middleportion.

FIG. 5 is an enlarged lengthwise sectional view of the opposite ends ofthe rotated guide bar shown in FIG. 4, with a block diagramrepresentation of associated coolant supply.

FIG. 6 is a fragmentary side view of one end of the rotated guide barshown in FIG. 4.

FIG. 7 is an enlarged sectional taken through the rotated guide bar.

FIG. 8 is a view of the guide bar in the direction of the arrows in FIG.4.

FIG. 9 is a lengthwise sectional view of a rotated guide bar accordingto another embodiment of the invention with a block diagram depiction ofthe associated coolant supply system.

DETAILED DESCRIPTION

In the following detailed description, certain specific terminology willbe employed for the sake of clarity and a particular embodimentdescribed in accordance with the requirements of 35 USC 112, but it isto be understood that the same is not intended to be limiting and shouldnot be so construed inasmuch as the invention is capable of taking manyforms and variations within the scope of the appended claims.

Referring to the drawings, and particularly FIG. 1, a lip rollingapparatus 10 of the type described above is shown.

A train of nested cups C (lying on their sides) is supplied from a cupforming machine 12. Typically, accumulating devices (not shown) may beused to insure a constant supply of nested cups to the lip curlingapparatus 10 via a conveyor 14.

A transition conveyor 14A receives the nested cups and feeds themaccurately into the center space between a set of feed rollers in a feedroller mechanism 16, described in detail in U.S. Pat. No. 6,135,754,incorporated herein by reference. As described therein, the feed rollermechanism 16 comprises a set of rollers each mounted for poweredrotation, and with the axes of rotation arranged about the center lineof a circle defined by the feed roller outer perimeters, so as to engagethe rims of the cups C to rotate the same. The rollers 16 are adjustablytilted slightly out of the plane of the spacing circle to create africtional force also tending to advance the cups through a preheatingoven 18.

The cup rims are heated in the oven 18 to be softened in preparation tobeing formed in the lip curling screw mechanism 20 in the well knownmanner. The cups are supported and guided on a set of oven guide bars22A, 22B, 22C while in the oven 18 while being exposed to heatingelements (not shown) in the oven 18. The spacing of each end of the setof three guide bars 22A, 22B, 22C is adjustable to be fit to the size ofcontainer be formed, as described in U.S. Pat. No. 6,093,010.

The cup feed rate established by the feed mechanism 16 is finelyadjustable to be closely matched to the rate that the cups are processedby the lip curling screw mechanism 20, as described above. In addition,the diameter of the circular space defined between the feed rollers mustbe adjustable if the machine 10 is to be used for variously sized cups.

The lip curling mechanism 20 also is adjustable quickly and easily to beable to form a lip on different container sizes, as is described indetail and claimed in U.S. Pat. No. 6,164,949, also incorporated hereinby reference.

Both of these adjustments may be made “on the fly”, i.e., when themachine is running, in order to more easily determine if a properadjustment has been accomplished, and to eliminate the need to interruptproduction in order to make adjustments.

A single electric motor M drives both the feed roller mechanism 16 andthe lip curling mechanism 20 as described in the patents referencedabove.

A control panel (not shown) and coolant connections to the curling screwmechanism 20 and guide bars 22 are also omitted in this view for thesake of clarity. A temperature control unit (not shown) maintains thetemperature of the coolant, so as to keep the temperature of the curlingscrews and guide bars in the proper range. Such temperature controllersare commercially available, a suitable controllers being Model TNY4 fromAEC (Applied Engineering Co.).

The oven guide bars 22 have left and right end spacing adjustmentmechanisms 24A, 24B located at respective ends of the oven 18. The oven18 itself can be formed in two halves, opened by a clam shell mechanism(not shown). In addition, the entire oven 18 with the end plates 26A,26B guide bars 22A, 22B, 22C and guide bar adjustment mechanisms 24A,24B may be swung away as described in U.S. Pat. No. 6,093,010.

Receptacles 17 are mounted to machine end plates 25 (only one shown inFIGS. 2A, 2B) connected by rods 19. The receptacles 17 can be releasedto allow connector rods 19, oven support plates 26A, 26B, guide baradjusting mechanisms 24A, 24B, guide bars 22A, 22B, 22C and the oven 18itself to be swung away by power cylinder 23. As mentioned above, twohalves of the oven 18 can also be swung open both by a conventionalclamshell mechanism as stated in U.S. Pat. No. 6,093,010.

FIG. 2 is a pictorial view of some of the components of the lip curlingapparatus 10 with the oven 18 and lip curling mechanism 20 omitted forclarity.

The guide bar adjustment mechanisms 24A, 24B are mounted on oven supportend plates 26A, 26B connected together with rods 21. Each guide baradjustment mechanism 24A, 24B includes three pivot arms 28, 30, 32, eachholding one end of a respective one of the three guide bars 22A, 22B,22C (best seen in FIG. 3).

The spacing of each set of ends of the guide bars 22A, 22B, 22C may beindependently adjusted by manual movement of a handle portion 34 or ahand wheel on pivot arm 28 as described in detail in U.S. Pat. No.6,093,010.

Connecting links 36, 38 create simultaneous movement of all three pivotarms 28, 30, 32. According to the teachings of the present invention,the lower middle guide bar 22B is rotated by a D.C. variable speed motor40 located at the entry end of the oven 18 mounted to plate 26A ovensupport end plate 26A, which drives a synchronous belt 42. A belttensioner 44 accommodates any adjustment movement of the rotated guidebar 22B.

FIGS. 4-8 show details of one embodiment of a rotated oven guide bar 22Baccording to the invention, which is composed of an inner fixed tube 46and an outer rotatable tube 48 patentably mounted on the inner fixedtube 46.

The outer tube 48 rotatable mounting includes two pairs of ceramichybrid bearings 50 located at either end of the inner fixed tube 46 torotatably support the outer rotated tube 48 on the inner fixed tube 46.Such bearings can run at higher temperatures than standard bearings, andthus are better able to operate at high speed under the high temperatureconditions in the oven 18.

The space between the two set of bearings 50 is largely occupied by aclosely fit fiberglass bushing 52 and the remaining space is filled witha high temperature lubricant. The fiberglass bushing 52 is closely fitwithin the outer rotated tube 48 to restrain the rotating outer tube andlimit any tendency to whip caused by any minor lack of straightnessthereof, as the outer tube 48 is rotated at high speed. The speed ofrotation of the outer tube 48 is on the order of several thousand rpm isthis high speed being necessary since the outer tube 48 is substantiallysmaller in diameter than the diameter of the cup rims.

Seals 54 are provided to retain the lubricant in the space between thefixed inner tube 46 and the rotated outer tube 48. The lubricant acts tolubricate the bearings 50 but also acts to conduct heat away from theouter tube 48 (which is heated by the oven heaters) and into the coolantflowing through inner fixed tube 46.

Coolant is supplied from a coolant source 56 flowing into and out ofelbow fittings 58 and 60 fixed at respective ends of the inner fixedtube 46, the temperature of which is maintained by a controller asmentioned above.

The rotation of the relatively small diameter outer sleeve 48 is at ahigh rate, i.e., on the order of 4000 rpm since the cup rims have asubstantially larger diameter, necessitating the higher rate of rotationof the sleeve 48 to maintain the lower desired rate of rotation of thenested cups, i.e., approximately 1000-1200 rpm.

The bearings 50 benefit from the fact that the temperature of the outertube 48 is desirably at approximately 150° F.-180° F., with the innerfixed tube 46 kept at around 30° F. less.

Thus, heat generated by the bearings 50 is conducted into the coolantflow and the bearings 50 will therefore have a much longer service life.

The outer tube 48 is rotated by the belt 42 engaging a toothed sheave 62attached to the outer tube 48 by an extension 64 fastened to the sheave62 by screws 65, the extension 64 threaded into the left end of theouter tube 48 as seen in FIG. 5.

A fixed outer cover 66 encloses a pair of split mounting collars 68, 70also included clamped together over the end of the fixed tube 46 bymeans of screws 72. The cover 66 is secured by screws 74 (FIG. 7).

The right end of the cover 66 has an opening on one side, exposing thetoothed sheave 62 to enable partial wrapping of the belt 42 around thetoothed sheave 62 (shown in FIGS. 3 and 3B) which enables driving theouter tube 48 at a high rotational speed.

The left end of the guide bar 22B is attached to the middle pivot arm 30of the adjustment mechanism 24A by a shoulder bolt 76 passing through aslotted opening 82 in a connector piece 78 secured to split collars 68,70 by screws 80.

The right end of the guide bar 22B is likewise attached to the otherguide bar adjustment mechanism 24B by a connector piece 84 secured tothe right end of fixed inner tube 46 attached with a shoulder bolt 86 tothe right end pivot arm 30. The connector piece 84 is attached to asplit collar 88 by screws 90 (FIG. 8) passed through a slot 92 in acover sleeve 94, held in place with screws 96 (FIG. 8).

The two adjustment mechanisms 24A, 24B are independently operable toenable creation of a slight skewing of the guide bars 22A, 22B, 22Cwhich can be set to create an axial driving force on the train of nestedcups by the rotation of the guide bar 22B, contributing to the axialadvancing force developed by the feed mechanism 16. This helps maintaina precisely set axial advance rate of the train of nested cups C.

The adjustable speed of the variable speed motor 40 allows fineadjustment of the rate of rotation of the train of nested cups C toachieve proper heating and the rate of advance to be very closelymatched to the rate at which the cups are processed in the lip curlingmechanism 20.

FIG. 9 shows a second embodiment in which the rotated guide bar 22B iscomprised of a single tube 94 which is supported by end supportassemblies 95 receiving a pair of rotating end fittings 96 affixed to arespective in sets of bearings 98 held by a split sleeve clamp 100.

A rotary union 102 is installed at each end to provide a fluidconnection to and from a coolant source 104 to the inside bore of theend pieces 96 and the inner space 106 within the tube 94, enablingcirculation of the coolant therethrough. The rotary union 102 ispreferably designed to have a larger than standard inside bore diameterto allow freer flow of coolant therethrough.

A toothed sheave 108 is affixed to the left end fitting 96 as by a key110 and exposed to enable engagement by a toothed belt driven by a motoras described above. A filter 112 may be provided to remove entrainedparticles to thereby prevent clogging of the internal passage of theunions 102.

1. In a lip rolling apparatus of the type including a feed rollermechanism for advancing a train of nested containers through apreheating oven included in said machine, with a set of tubular ovenguide bars extending through said oven, each guide bar mounted at eitherend to a respective adjustment mechanism at either end of said oven,said guide bars guiding said train of nested containers during theiradvance through said oven with a coolant flow circulated through saidguide bars via fluid connections at either end of each of said guidebars, and a lip rolling mechanism receiving said train of nestedcontainers after being advanced out of said oven, the improvementcomprising: one of said oven guide bars rotatably mounted and a rotarydrive rotating said one guide bar on said adjustment mechanism.
 2. Thelip rolling apparatus according to claim 1 wherein said one guide barincludes a fixed inner tube and an outer tube rotatably mounted on saidfixed inner tube.
 3. The lip rolling apparatus according to claim 2wherein one or more bearings at either end of said fixed tube supportssaid outer tube on said fixed inner tube.
 4. The lip rolling apparatusaccording to claim 3 wherein a closely fit bushing is interposed betweensaid inner fixed tube and said rotatable outer tube intermediate thelength thereof to stabilize said outer tube when being rotated.
 5. Thelip rolling apparatus according to claim 3 wherein an annular spacebetween said outer tube and said inner fixed tube between said one ormore bearings at each end of said fixed inner tube is filled with alubricating liquid to also act to carry heat from said outer tube intosaid coolant flowing through said inner fixed tube.
 6. The lip rollingapparatus according to claim 1 wherein said rotary drive includes avariable speed D.C. motor enabling adjustment of the speed of rotationof said one rotatable guide bar.
 7. The lip rolling apparatus accordingto claim 6 wherein said variable speed D.C. motor drives a belt whichengages a toothed sheave attached to one end of said rotary outer tube.8. The lip rolling apparatus according to claim 1 wherein said one guidebar has an end piece at either end received in bearings carried by anassembly at either end mounted to one of said adjustment mechanisms. 9.The lip rolling machine according to claim 8 wherein a rotary union ateach end of said one tubular guide bars provides a rotary fluidconnection for supplying coolant circulated through said one tubularguide bar.